Hodgkin's Lymphoma

Synonym: Hodgkin's disease

Hodgkin's lymphoma is a malignant tumour of the lymphatic system that is characterised histologically by the presence of multinucleated giant cells (Reed-Sternberg cells) and associated abnormal and smaller mononuclear cells originating from B lymphocytes in the germinal centres of lymphoid tissue.

Classification

Accurate classification of the type and accurate staging of the disease will determine the most favourable treatment options and prognosis. Hodgkin's lymphoma is classified into two distinct entities^[1] :

• Classical Hodgkin's lymphoma (more common):
  • Nodular sclerosis
  • Mixed cellularity
  • Lymphocyte-rich
  • Lymphocyte-depleted
• Nodular lymphocyte-predominant Hodgkin's lymphoma (NLPHL).

There is no difference in the prognosis or management of the different subtypes of classical Hodgkin's lymphoma. In Europe and North America, nodular sclerosis classical Hodgkin's lymphoma accounts for 70% of all classical Hodgkin's lymphoma. Lymphocyte-depleted classical Hodgkin's lymphoma is more prevalent in immunocompromised patients and is seen more commonly in developing countries, where it has a strong association with Epstein-Barr virus (EBV) infection^[2] .

NLPHL is distinct histologically and Reed-Sternberg cells are not present, it has a risk of transformation to high-grade non-Hodgkin's lymphoma and is managed differently from classical Hodgkin's lymphoma. The rest of this article is about classical Hodgkin's lymphoma.

Epidemiology^[2]

• The annual incidence of Hodgkin's lymphoma in the UK is 2.7/100,000 with a slight male predominance.
• There is a peak in incidence in young adults aged 20-34 years, with a further peak observed over 70 years.

Risk factors

• EBV has been found in the Reed-Sternberg cells of about 50% of patients with Hodgkin's lymphoma.
• Patients who have previously developed mononucleosis have an increased risk of developing Hodgkin's lymphoma.
• Other risk factors include human immunodeficiency virus (HIV), immunosuppression and cigarette smoking.

Presentation

• Most patients present with an enlarged but otherwise asymptomatic lymph node, typically in the lower neck or supraclavicular region.
• Mediastinal masses are frequent and are sometimes discovered on a routine CXR.
• Patients might complain of chest discomfort with a cough or dyspnoea.
• Systemic symptoms of drenching night sweats, unexplained fever >38°C, and weight loss of >10% over six months, are termed B symptoms and are identified in approximately 25% of patients^[2] .
• Alcohol-induced pain at sites of nodal disease is specific but occurs in fewer than 10% of patients.
• Findings on examination include lymphadenopathy, hepatomegaly, splenomegaly, and superior vena cava syndrome; there may also be features caused by paraneoplastic syndromes - eg, cerebellar degeneration, neuropathy or Guillain-Barré syndrome.

Differential diagnosis

• Infectious mononucleosis
• AIDS
• Non-Hodgkin's lymphoma
• Tuberculosis
• Leukaemia
• Sarcoidosis
• Myeloma
• Toxoplasmosis
• Cytomegalovirus infection
• Tularaemia

Investigations

• FBC: to exclude leukaemia, mononucleosis and other causes of lymphadenopathy. The degree of any anaemia, leukocytosis and lymphopenia are prognostic indicators.
• Tests for possible differential diagnoses - eg, tests for infectious mononucleosis.
• ESR: an ESR of greater than 70 carries an unfavourable prognosis.
• Liver function and serum protein tests: the level of any rise in lactate dehydrogenase (LDH) and fall in albumin levels has prognostic significance.
• HIV tests are necessary in patients with suspected Hodgkin's lymphoma.
• Fine needle aspiration samples should not normally be used as the sole tissue for diagnosis.
• Lymph node biopsy:
  • Pathological diagnosis should be made from a sufficiently large specimen or excisional lymph node biopsy to provide samples for fresh frozen and formalin-fixed samples.
  • Excisional node biopsy is better than fine needle or core needle biopsy, as it allows the diagnosis of lymphomas based on the morphology of the lymph node, which is not offered by needle biopsy.
• CXR: assess any intrathoracic lymphadenopathy and mediastinal expansion.
• CT scans of the thorax and abdomen are required for staging Hodgkin's lymphoma.
• Lymphangiography: may be useful if there is subdiaphragmatic presentation of Hodgkin's lymphoma with equivocal abdominal CT findings, or there is subdiaphragmatic presentation of Hodgkin's lymphoma with the intention to treat with radiotherapy alone.
• Gallium scans: can be useful if CT scanning produces equivocal results. They are performed if mediastinal or hilar nodes are involved and as a baseline in patients with bulky disease, for better determination of response during and after therapy.
• Bone marrow biopsy is indicated for staging purposes.

Staging and risk assessment

• FBC, ESR and blood chemistry including CRP, alkaline phosphatase, LDH, liver enzymes, albumin and TSH.
• Pre-treatment blood evaluation should include hepatitis B virus (HBV), hepatitis C virus (HCV) and HIV^[2] .
• Patients should be staged with a contrast-enhanced CT scan covering the neck, chest, abdomen and pelvis. An initial positron emission tomography (PET)/CT scan is highly recommended^[2] .
• It was common practice to limit bone marrow evaluation to patients with advanced-stage disease or B symptoms. It is now generally accepted that PET/CT can accurately detect marrow involvement and evaluation by biopsy is often unnecessary^[2] .
• Staging laparotomy is not recommended.

Staging

Patients with early-stage disease should be classified into favourable or unfavourable prognosis, depending on the presence or absence of mediastinal adenopathy, presence of symptoms, level of ESR and number of lymph node sites involved^[2] .

Ann Arbor staging system for Hodgkin's lymphoma:

• Stage I: involvement of one lymph-node region or lymphoid structure (eg, spleen, thymus, Waldeyer's ring).
• Stage II: two or more lymph-node regions on the same side of the diaphragm.
• Stage III: lymph nodes on both sides of the diaphragm.
  • Stage III (1): with splenic, hilar, coeliac, or portal nodes.
  • Stage III (2): with para-aortic, iliac, or mesenteric nodes.
• Stage IV: involvement of extranodal site(s) beyond that designated E (see below).
• Modifying features:
  • A: no symptoms.
  • B: fever, drenching night sweats, weight loss greater than 10% in six months.
  • X: bulky disease: greater than a third widening of mediastinum or greater than 10 cm maximum diameter of nodal mass.
  • E: involvement of single, contiguous, or proximal extranodal site.

Disease is further classified into limited, intermediate or advanced:

• Limited disease: up to IIB with no risk factors.
• Intermediate disease: up to IIB with at least three involved lymph-node areas or high ESR (ESR over 50 mm/h without B symptoms, or over 30 mm/h with B symptoms; B symptoms are defined as fever, night sweat, weight loss).
• Advanced disease:
  • Stage IIB with large mediastinal mass (more than one third of the horizontal chest diameter) or extranodal disease.
  • Any stage III or above.

Management^[4]

Before treatment, patients should be assessed for risk of acute and/or long-term complications. Cardiac and pulmonary function tests are mandatory, and consultation with an ear, nose and throat specialist should be considered (particularly for patients with involvement of the head and neck region). The patient may also need reproductive counselling if they have not yet started a family, as treatment may compromise fertility. For male patients, pre-treatment semen cryopreservation should be offered where possible. For female patients, pre-treatment review of options with a fertility specialist should be considered^[2] .

Initial therapy is based on the histology of the disease, the anatomical stage and the presence of poor prognostic features. Patients with early-stage disease are typically treated with combined modality strategies with courses of combination chemotherapy followed by involved-field radiation therapy, while those with advanced-stage disease receive a longer course of chemotherapy often without radiation therapy. Newer agents including brentuximab vedotin are now being incorporated into frontline therapy and these new combinations are becoming a standard of care.

High-dose chemotherapy (HDCT) followed by an autologous stem cell transplant (ASCT) is the standard of care for most patients who relapse following initial therapy. For patients who fail HDCT with ASCT, brentuximab vedotin, PD-1 blockade, non-myeloablative allogeneic transplant or participation in a clinical trial should be considered.

Both chemotherapy and radiation therapy increase the risk of developing secondary solid tumours - eg, cancers of the lung, breast, and stomach.

Vaccinations: polyvalent pneumococcal vaccine and influenza vaccine should be given to all patients with Hodgkin's lymphoma. Meningococcal group C conjugate vaccine and Haemophilus influenzae type b vaccine are also recommended, especially for patients receiving treatment and those with asplenia or splenic dysfunction^[5] .

Chemotherapy

• Effective but carries an increased risk of leukaemia. The peak in risk is seen about five years after the initiation of chemotherapy. The risk is higher in patients who undergo splenectomy and who have advanced disease; the risk is unaffected by concomitant radiation therapy.
• Chemotherapy is normally based on certain combinations^[2] :
  • ABVD: doxorubicin (used to be called Adriamycin®), bleomycin, vinblastine and dacarbazine.
  • BEACOPP: consists of bleomycin, etoposide, doxorubicin (Adriamycin®), cyclophosphamide, vincristine (Oncovin®), procarbazine and prednisolone.
  • If therapy is required in pregnancy, the general consensus is that ABVD is the regimen of choice if multi-agent chemotherapy is to be used.
• Any patient with severe neutropenia should be given antibiotic prophylaxis with chemotherapy.
• Recombinant human granulocyte colony-stimulating factor (rhG-CSF) stimulates the production of neutrophils and may reduce the duration of chemotherapy-induced neutropenia and thereby reduce the incidence of associated sepsis^[5] .

Radiotherapy

• Classic pattern is extended radiation field in a supradiaphragmatic mantle involving all nodal areas above the diaphragm in local disease with prophylactic abdominal irradiation in stage I and stage II disease.
• More extensive radiotherapy reduces the risk of relapse but increases the risk of late mortality from other causes.
• Radiotherapy should not normally be omitted for patients presenting with bulky early-stage disease^[2] .

Treatment regimes

There is some variation between the different guidelines. The following regimes are recommended by the European Society for Medical Oncology (ESMO). The choice of treatment will depend on the stage of the disease, the histological subtype and favourable prognostic factors^[2] :

• Early-stage disease:
  • Standard of care for patients with favourable and unfavourable early stage is chemotherapy using ABVD and radiotherapy, with more cycles of chemotherapy for patients with unfavourable prognosis.
  • A treatment option for unfavourable early stage is BEACOPP and then ABVD plus radiotherapy.
• Advanced-stage disease:
  • Patients aged 16 to 60 years with advanced-stage disease should receive either six to eight cycles of ABVD or six cycles of escalated BEACOPP. Younger and older patients should be assessed on an individual basis.
  • Patients treated with BEACOPP who achieve an end-of-treatment PET-negative remission do not require consolidation radiotherapy to residual tissue.
  • Patients treated with ABVD should be considered for radiotherapy to sites of original bulk or residual tissue >1.5 cm.
  • Patients who remain PET-positive on completion of therapy require biopsy assessment or close clinical/radiological surveillance for early progression.

Primary resistant and relapsed classical Hodgkin's lymphoma^[6]

• Repeat biopsy is recommended for patients thought to have relapsed, and should be considered in those who have residual lesions after treatment. PET/CT is the preferred restaging modality after salvage therapy (high-dose chemotherapy).
• ASCT is the standard treatment for patients with primary resistant disease or with relapsed disease who achieve an adequate response to salvage chemotherapy. ASCT is not recommended in those failing to achieve an adequate response.
• The choice of a first-line salvage regime in patients eligible for ASCT should be based on individual patient factors. Regimens containing stem cell toxic agents (eg, carmustine and melphalan) should be avoided if possible until stem cells have been successfully collected and cryopreserved if ASCT is planned.
• In patients not eligible for ASCT, combined therapy (chemotherapy and radiotherapy) should be considered especially in:
  • Early-stage relapse.
  • Patients who have not received prior radiotherapy or who have relapsed outside of the initial radiotherapy field.
• In patients unlikely to tolerate the toxicities associated with more intensive regimens, palliation with either a single agent or with a multi-agent oral regimen with or without intravenous vinblastine should be considered.
• Early consideration of involvement of palliative care services is recommended, particularly in those not eligible for high-dose therapy.
• For patients who do not respond to high-dose chemotherapy with ASCT, brentuximab vedotin, palliative chemotherapy, non-myeloablative allogeneic transplant or participation in a clinical trial should be considered^{[7, 8]} .
• Allogeneic transplantation using a reduced-intensity conditioning regimen is the treatment of choice for younger patients with a suitable donor and chemo-sensitive disease following failure of ASCT.
• A second autologous transplant is a reasonable clinical option in selected patients with late relapse following ASCT.
• The use of radiotherapy should be considered in cases of local relapse or relapse at sites where local disease is dominating the clinical picture.
• Salvage radiotherapy alone may be considered a reasonable treatment option in selected patients not eligible for ASCT, especially for older patients with relapsed Hodgkin's lymphoma with a favourable prognosis and limited-stage disease at relapse.

Follow-up^[2]

• Patients are usually followed with intermittent outpatient clinical review for two to five years following first-line therapy. There is no proven role for routine surveillance CT or PET/CT imaging in patients who are otherwise well following first-line therapy.
• Patients should be made aware that they are at an increased lifetime risk of second neoplasms, cardiovascular and pulmonary disease and infertility.
• Regular lifestyle advice should be offered to reduce the secondary neoplasms and cardiovascular risk, including complete avoidance of smoking and management of cardiovascular risks such as hypertension, diabetes mellitus and hyperlipidaemia.
• Patients who have had radiotherapy to the neck and upper mediastinum should have regular thyroid function checks. Hypothyroidism can occur up to 30 years after radiotherapy.
• Patients should only receive irradiated blood products for the rest of their lives.

Complications

• Leukaemia, especially acute myeloid leukaemia, may occur in patients treated with chemotherapy or combined chemotherapy and radiotherapy.
• Second solid tumours, especially of the colon, lung, bone, breast, and thyroid, can occur in patients who received radiation therapy with or without chemotherapy^[9] . Cancer screening should be conducted regularly.
• The risk of breast cancer is greatest in women treated with supradiaphragmatic radiotherapy (SRT) during adolescence and young adulthood, although an increase in risk is shown in most studies with SRT up to the age of 30-40 years, which persists for at least 20-25 years after treatment^[10] .
• An increased risk has also been found for melanoma, non-Hodgkin's lymphoma, soft-tissue sarcoma, salivary gland cancers and pancreatic cancer.
• Other complications of irradiation include hypothyroidism and cardiovascular disease.
• Other complications of chemotherapy include male infertility and female infertility.

Prognosis

• Both localised and advanced Hodgkin's lymphoma can be cured in most patients.
• With modern treatment strategies, 80-90% of patients achieve permanent remission and can be considered cured^[11] .
• Poor prognostic indicators include^[12] :
  
  • Increasing tumour burden and extension of disease.
  • Increasing age.
  • Male.
  • Constitutional symptoms (unexplained fever above 38°C, drenching night sweats and weight loss).
  • Anaemia, leukocytosis, lymphopenia, monocytosis.
  • Low levels of serum albumin.
  • Increasing ESR.
  • Elevated beta-2 microglobulin.
  • Biohumoral factors (IL-10, IL-6, sCD30, TNF, TARC).
  • Circulating DNA of cellular and viral (EBV) origin.
  • Genetic background.
• Despite the high cure rates, long-term survivors have increased mortality^[2] :
  • During the first 5-10 years of follow-up, the main cause of increased mortality is the disease itself, especially in those with unfavourable prognosis.
  • However, mortality remains significantly elevated more than 20 years after treatment. The main causes of long-term, non-relapse morbidity and mortality are second neoplasms and cardiac disease, but also include pulmonary disease and infections.